DESCRIPTION (Adapted from the Applicant's Description): The overall aim of this revised application is to carefully determine the time course and extent of leukocyte (neutrophil and macrophage) entry into the spinal cord (T10 level) following spinal cord contusion, and to determine if this influx is related to the development of secondary damage. Evidence from studies of neocortical contusion injury and central nervous system (CNS) ischemia/reperfusion damage indicate that neutrophils, in particular, are associated with oxidative damage to healthy tissue at sites of injury. Neutrophils can enter sites of CNS trauma within a few hours and produce damaging free radicals which can contribute to the delayed neuronal damage and death that is known to occur. The major emphasis of the first specific aim is therefore to examine neutrophil accumulation at different times following injury. The second specific aim is to examine means of limiting the neutrophil response, thus hopefully limiting the extent of neuronal damage and enhancing behavioral measures of motor function.